Cleaning tape with improved edge adhesive

ABSTRACT

A cleaning tape is edge-stabilized using an adhesive that is solvent resistant. The edge-stabilizing adhesive is a one-step cross-linkable formulation of polyvinyl alcohol, ammonium zirconium carbonate, an acetylinic surfactant and a non-silicone defoaming agent. The formulation is applied to the sides of a woven cotton cleaning tape roll and then is allowed to dry and cure. The resulting cleaning tape can be used in a surface buffing operation in which a solvent is applied to the cleaning tape, without contamination of the surface to be buffed by fibers from the tape or by the edge-stabilizing adhesive.

This application is a division of application Ser. No. 08/369,373, filedJan 6, 1995 now U.S. Pat. No. 5,571,601.

BACKGROUND OF THE INVENTION

This invention relates to fabric tape formed into a roll andparticularly to such a roll having adhesive applied to the sides thereoffor stabilizing the edges of the fabric tape.

It is known to provide rolls of fabric tape for a number ofapplications, including, for example, buffing the uppermost or "lube"layer of a plate formed as the disk component of a so-called fixed or"hard" information storage disk drive. As is known to those who areskilled in the art, the process of "lube buffing" the top surface of thehard disk plate is a finishing step in the process of manufacturing thedisk. For this purpose it is preferred to employ a woven cotton tape. Itis known to apply an adhesive to the edge of the tape in order toprevent the tape from fraying at the edges. If the tape is allowed tofray at the edges, cotton fibers may be deposited on the disk plate,resulting in contamination of the disk plate. As the desired informationstorage density on hard disks has increased, the tolerances forcontaminants have become correspondingly more stringent.

The lube buffing process typically involves impregnating the cotton tapewith a solvent such as a methyl alcohol solution. The solvent helps toevenly distribute the lubricant on the surface of the lube layer of thedisk plate, and to aid in removing contaminants from the disk plate.However, applicants have become aware of a problem encountered in lubebuffing with a solvent-impregnated tape having an edge-stabilizingadhesive. In particular, the solvent tends to dissolve the edgeadhesive, causing the adhesive to be deposited on the disk plate whichresults in contamination of the disk plate.

Although it is possible to apply the tape to the lube layer surface insuch a manner that the edges of the tape are maintained at a distancefrom the lube layer surface, such a manner of applying the tape to thesurface fails to use the tape efficiently, and entails someinconvenience in handling the tape during lube buffing.

OBJECTS OF THE INVENTION

It is accordingly an object of the invention to provide anedge-stabilized cleaning tape that does not suffer from thedisadvantages described above. In particular, it is an object to providean edge-stabilized cleaning tape which can be impregnated with asolvent, and the entire surface of which can be applied to the surfaceto be cleaned, without having the edge-stabilizing adhesive depositedupon the surface to be cleaned.

SUMMARY OF THE INVENTION

In accordance with the present invention, the foregoing objects are metby the provision of a cleaning tape roll which includes a fabric tapewound around a core so that opposite edges of the tape form opposedsubstantially flat sides of the roll, and a dried adhesive layer on thesides of the roll for stabilizing the edges of the tape, with theadhesive being substantially solvent resistant. By providing a solventresistant edge-stabilizing adhesive on a cleaning tape roll,contamination of the surface to be cleaned either by fibers releasedfrom the edge of the fabric tape, or from dissolved edge adhesive, canbe substantially avoided or eliminated.

According to further aspects of the invention, the adhesive layerincludes cross-linked polyvinyl alcohol and a cross-linking agent suchas ammonium zirconium carbonate.

According to another aspect of the invention, there is provided a methodof forming an edge-stabilized cleaning tape roll which includes thesteps of providing a roll of fabric tape wound around a core so thatopposite edges of the tape form opposed substantially flat sides of theroll, applying a cross-linkable adhesive formulation to the flat sidesof the roll, and allowing the applied adhesive formulation to dry, cureand cross-link.

According to another aspect of the invention, the cross-linkableadhesive formulation can be stored for 24 hours or more beforeapplication to the sides of the tape roll. Such an adhesive formulationcan be conveniently stored and/or transported prior to application.

According to yet another aspect of the invention, there is provided asolvent-resistant adhesive formulation for edge-stabilizing a roll offabric tape, including an aqueous solution of polyvinyl alcohol, across-linking agent and at least one surfactant.

According to further aspects of the invention, the adhesive formulationincludes an acetylinic surfactant and a non-silicone defoaming agent,the cross-linking agent includes ammonium zirconium carbonate, and theproportion of the polyvinyl alcohol to the cross-linking agent issubstantially 10:1. Such a formulation provides a solvent-resistantedge-stabilizing adhesive which can be formulated and stored well inadvance of application, and which dries and cures after application.

It is not intended that the invention be summarized here in itsentirety. Rather, further features, aspects and advantages of theinvention will be set forth in or be apparent from the followingdescription and drawings. In the drawings:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a cleaning tape roll provided inaccordance with the present invention; and

FIG. 2 is a front elevational view of the tape roll of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIGS. 1 and 2, a tape roll 10 is formed of a fabrictape 12 wound around a core 14. The core 14 may be formed, for example,of molded plastic. The sides 16 and 18 of the roll 10 are formed byrespective edges 20 and 22 of the tape 12. Preferably the tape 12 is awoven cotton fabric to which a rigorous cleaning process has beenapplied so that the tape 12 exhibits a substantially uniformcleanliness. However, the tape may be formed of fibers that arepartially or entirely non-cotton, including synthetic fibers, and thetape may be a non-woven material. A typical size for the tape roll 10 is1" wide by 8" in diameter.

As will be understood by those who are skilled in the art, there are twowell known techniques for forming a cleaning tape roll.

According to the first technique, known as the "unwind-slit-rewind"technique, a relatively broad fabric sheet is unwound from a spindle andslit in the direction of unwinding using one or more heated blades(typically, for example, 10 to 40 blades) to form narrow fabric tapeswhich are then respectively rerolled on separate cores.

According to the second of the two techniques referred to above, therelatively broad sheet of fabric, while still wound around a spindle toform a substantially cylindrical fabric-and-spindle assembly, is cut ina direction normal to the longitudinal axis of the fabric-and-spindleassembly, and at a distance from one end of the assembly equal to thedesired width of the tape roll, so that both the fabric and the spindleare cut in a single operation resulting in a tape roll of the desiredwidth. Each subsequent cut is performed at the same distance from thenewly formed end of the fabric-and-spindle assembly resulting insuccessive formation of tape rolls. This second technique is known asthe "single knife slicing" technique.

It is contemplated by the present invention that either of the twotechniques described above can be employed, provided only that theresulting tape roll has sides that are substantially flat and even. The"single knife slicing" technique is advantageous in that, with asuitable slicing knife, rolls with quite flat and even sides areproduced. However, the single knife slicing technique placesconsiderable demands on the slicing knife, particularly in connectionwith slicing through the spindle. To moderate such demands, it may benecessary to provide a spindle that is made of a relatively softmaterial, such as cardboard or paper, rather than plastic.

Alternatively, the unwind-slit-rewind technique can be used if the tapeis rewound with sufficient control (e.g., sufficiently slowly) so thatthe re-wound roll exhibits flat and smooth sides, with the respectiveedges of the tape being brought into registry as the tape is rewound.One advantage of the unwind-slit-rewind technique is that the core neednot be selected with a view to facilitating slicing, as in the singleknife slicing technique. Although unheated blades are normally used inthe unwind-slit-rewind technique, it is also contemplated that heatedblades may be used.

In any event, regardless of the technique used to form the tape roll, anadhesive formulated in a manner to be described below is applied to thesides 16 and 18 of the tape roll 10 so that adhesive layers 24 and 26are respectively formed on the sides 16 and 18. The adhesive is allowedto dry and cure, and then the adhesive layer may be sanded to produce asmooth adhesive layer of uniform thickness.

According to a preferred embodiment of the invention, a concentratedadhesive formulation is formed as an aqueous solution of polyvinylalcohol, a cross-linking agent, and one or more surfactants ordispersants.

A satisfactory type of polyvinyl alcohol is known as "Airvol 350",available from Air Products and Chemicals, Inc., Allentown, Pa. Asuitable cross-linking agent is an ammonium zirconium carbonate solutionsuch as is sold under the designation "Bacote 20" by Magnesium Elektron,Inc., Flemington, N.J. This cross-linking agent will cause the adhesiveto cross-link (cure) at substantially room temperature. The surfactantspreferably include an acetylinic surfactant, such as "Surfynol S.E."(available from Air Products), for emulsifying the polyvinyl alcohol,and an auxiliary defoaming agent such as the nonsilicone defoamer knownas "DEE-FO 97-2", supplied by Ultra Additives.

A preferred adhesive concentrate is prepared according to the followingformula:

    ______________________________________                                        Ingredient     % (by weight)                                                  ______________________________________                                        Water          90.027                                                         Airvol 350     8.360                                                          Bacote 20      0.832                                                          Surfynol S.E.  0.615                                                          DEE-FO 97-2    0.166                                                          ______________________________________                                    

The adhesive concentrate is prepared by adding the first threeingredients in the order given, with mixing by a mechanical mixer andwith heating up to around 180°-190° F. to aid in dissolving. The lasttwo ingredients are added during cooling to room temperature and withstirring.

Prior to application, the concentrate is diluted by adding up to fourparts by weight of water to six parts of concentrate. The dilutedadhesive may be applied to the sides 16 and 18 of the tape roll by meansof a brush or a two-pad pressure roller. The amount of dilution of theadhesive, and the pressure applied to the application rollers, areselected so that the dilute adhesive penetrates the sides of the taperoll to the extent of 1-3 threads. A doctor knife, or the like, is usedto dispense an appropriate amount of the dilute adhesive onto therollers. A suitable coating device is the Union Series #5, Model A, 14"Roller Coater available from The Union Tool Corp., Warsaw, Ind.

After application to the sides of the tape roll, the dilute adhesive isallowed to dry and cure at room temperature over a period of about 48 to72 hours. With the formulation described above, cross-linking takesplace only during the drying process.

After the adhesive layer 24 and 26 has dried, the same is sanded,preferably with vacuum, so that a smooth and clean adhesive layer 24 and26 is respectively provided on the sides 16 and 18 of the tape roll 10.The resulting adhesive layers 24 and 26 satisfactorily stabilizes theedges 20 and 22 of the tape 12, while substantially resisting polarsolvents such as methyl alcohol, isopropyl alcohol and the like.Substantial resistance is also provided to nonpolar solvents. In FIG. 1,a portion of the tape 12 is depicted as partially unrolled from the taperoll 10 during use in order to show adhesive layers 24 and 26 embeddedin the edges 20 and 22 of the tape 12 when unrolled.

Polyvinyl alcohol was selected for the preferred formulation as beingsatisfactorily cross-linkable and nontoxic, while providing thenecessary hardness after cure to permit sanding and also providing thedesired amount of penetration into the edge of the fabric tape. It iscontemplated to use cross-linking agents other than ammonium zirconiumcarbonate.

The surfactants are provided to promote satisfactory mixing of theadhesive formulation and also to prevent foaming, so that a smooth,nonfoamed adhesive film can be applied to the sides of the tape roll. Itis to be noted that if foam were present in the applied adhesive,irregularities in the adhesive layer might result.

Uniformity in the adhesive layer is also promoted by using a wovencotton fabric tape that has been scrupulously cleaned to provide uniformcleanliness so that the adhesive is uniformly absorbed by the sides ofthe tape roll.

It is also to be noted that the formulation described above is of the"one-step" type; that is, cross-linking does not begin upon the mixingof the adhesive and the cross-linking agent, but rather is deferreduntil drying. This is advantageous in that the adhesive concentrate canbe prepared well ahead of time before application and stored and/ortransported conveniently in a ready-to-dilute or ready-to-apply form. Itis believed that the formulation described above has a shelf life thatis indefinite, i.e., on the order of one year or more.

In the preferred formulation described above, the proportion ofpolyvinyl alcohol to cross-linking agent was substantially 10:1, butproportions of those two ingredients within the range of 5:1 to 100:1are also contemplated by the invention.

With a cleaning tape roll provided according to the present invention,lube buffing may be performed using a fabric tape impregnated with asolvent, while avoiding contamination of the hard disk plate by eitherone of fibers released from the edge of the tape or adhesive applied tostabilize the edge of the tape.

It is also within the contemplation of the invention to use other typesof adhesives, such as acrylic adhesives, provided only that the same arecrosslinkable and provide the necessary degree of hardness when cured.Acrylic adhesives are known which are self-crosslinking. Such adhesivesmay require heat curing at temperatures substantially above roomtemperature for full crosslink development, such as 275° F., and suchheat cured adhesives are within the contemplation of the presentinvention. Other cross-linkable adhesives may also be employed, whetherself-crosslinking or requiring a cross-linking agent, and whethercurable at room temperature, or at substantially higher temperature.

The above description of the invention is intended to be illustrativeand not limiting. Various changes or modifications in the embodimentsdescribed may occur to those skilled in the art and these can be madewithout departing from the scope or spirit of the invention.

What is claimed is:
 1. A method of forming an edge-stabilized cleaningtape roll, comprising the steps of:providing a roll of cleaning tapewound so that opposite edges of said cleaning tape form opposedsubstantially flat sides of said roll; applying a cross-linkableadhesive formulation to said flat sides of said roll to form an adhesivelayer; and allowing said applied adhesive formulation to dry, cure andcrosslink to form said edge-stabilized cleaning tape roll, wherein saidadhesive formulation comprises at least one defoaming surfactant in anamount sufficient to promote mixing of the adhesive formulation.
 2. Amethod according to claim 1, wherein said allowing step is performed atsubstantially room temperature.
 3. A method according to claim 1,wherein said allowing step is performed at a temperature above roomtemperature.
 4. A method according to claim 1, further comprising thestep of sanding said flat sides of said roll having said dried adhesivethereon to smooth said adhesive layer.
 5. A method according to claim 1,further comprising the step of storing said cross-linkable adhesiveformulation for at least 24 hours before said applying step.
 6. A methodaccording to claim 1, wherein said cross-linkable adhesive formulationcomprises polyvinyl alcohol.
 7. A method according to claim 6, whereinsaid cross-linkable adhesive formulation comprises ammonium zirconiumcarbonate.
 8. A method according to claim 1, wherein said cleaning tapeis a woven cotton fabric.
 9. The method of claim 6, wherein saidcleaning tape is a woven cotton fabric.
 10. The method of claim 1,wherein said adhesive layer is resistant to solution by polar solvents.11. The method of claim 1, wherein said adhesive layer is substantiallyresistant to solution by a solvent selected from the group consisting ofmethyl alcohol and isopropyl alcohol.
 12. The method of claim 8, whereinsaid adhesive formulation comprises a cross-linking agent.
 13. Themethod of claim 12, wherein said cross-linking agent comprises ammoniumzirconium carbonate.
 14. The method of claim 8, wherein said adhesiveformulation comprises polyvinyl alcohol.
 15. The method of claim 11,wherein said adhesive formulation comprises an aqueous solution ofpolyvinyl alcohol, a cross-linking agent and at least one surfactant.16. The method of claim 11, wherein said adhesive formulation comprisesa plurality of surfactants.
 17. The method of claim 16, wherein saidplurality of surfactants comprises an acetylinic surfactant and anonsilicone defoaming agent.
 18. The method of claim 15, wherein saidpolyvinyl alcohol and said cross-linking agent are present in aproportion within the range of 5:1 to 100:1:.
 19. The method of claim13, wherein said formulation further comprises polyvinyl alcohol.